This invention relates to an electrical energy meter such as used by power generation and transmission companies, and, more particularly, to a revenue accuracy meter and meter system that calculates multi-level energy losses.
Utility power distribution generally is divided into three segments: generation, transmission and distribution. More particularly, power is generated by a power generation facility, i.e., a power generator or power plant. The power generator supplies power through step-up subtransmission transformers to transmission lines. To reduce power transportation losses, the step-up transformers increase the voltage and reduce the current. The actual transmission line voltage conventionally depends on the distance between the subtransmission transformers and the users or customers.
Distribution substation transformers reduce the voltage from transmission line level to generally a range of about 2-35 kV. The primary power distribution system delivers power to distribution transformers that reduce the voltage still further, i.e., to about 120 V to 600 V.
Prior to electric utility deregulation, one entity or xe2x80x9celectric utilityxe2x80x9d usually owned the power generation, transmission and distribution segments. This utility would charge its customers according to the amount of energy the customer used. Energy usage could be determined by metering the usage at the customer""s location. Such metering was relatively simple and inexpensive because of the low voltages at these metering locations.
Electrical utilities would account for energy losses during transmission and distribution when calculating its rate structure. In other words, the utility would allocate the energy losses between its customers, thereby charging each customer a fair portion for the energy losses that occurred in transmitting the energy to the customer.
Utility deregulation, however, allows for separate ownership of the individual segments (and sub-segments) of a power generation, transmission and distribution system. Thus, one entity may own and maintain a power generation facility, which delivers energy to a transmission system that may be owned and maintained by another entity, which then delivers energy to a distribution system which may be owned and maintained by yet another entity.
Consequently, it is important that each entity know the exact amount of energy being supplied by it to another company (or received from another company). In other words, the power generator should know the amount of energy it is supplying to the transmission company and the transmission company should know the amount of energy it is supplying to the distribution company. Therefore, it is important to know the amount of energy being delivered at each point of delivery to each entity. This way, each entity knows the amount of energy it is selling or receiving at the various points of delivery throughout the system.
However, there are usually high voltages at these points of delivery, such as after step-up transformers and along transmission lines. Thus, because of the high voltages, it is difficult and expensive to connect a meter at such points to monitor the energy values. In addition, by adding additional meters and transformers to such systems, maintenance becomes more difficult and reliability may decrease.
Metering at different locations is also important because of energy losses that occur during transmission and distribution. Specifically, transformers and transmission lines cause the majority of energy losses during transmission and distribution. Moreover, each entity itself consumes energy in its day to day activities, such as for lighting, controls and heating. It is important to account for these losses since, with deregulation, it becomes important to know the exact amount of energy that is delivered at different points of delivery along the system.
Consequently, and especially with deregulation, there is a need for better management and accounting of energy supply and delivery. There is also a need to determine the amounts of energy being delivered at different points in a generation, transmission and distribution system, without increasing the number of meters in the system. There is also a need for the simplification of energy metering.
Moreover, each supplier, user and deliverer should be able to communicate with each other, and transfer information regarding the quantity, and, if desired, the quality, of the energy being transferred into and out of their particular portion of the generation and transmission system. Thus, the management, accounting and metering of energy is becoming more and more important.
Accordingly, it is desirable to provide an inexpensive and reliable metering device that provides information about energy being delivered at different points in a utility generation and transmission system. Moreover, it is desirable to eliminate meters, or the need for meters, at certain locations in utility transmission and distribution systems.
The present invention advantageously provides a loss compensator for use in or in connection with an electronic revenue access meter to provide it with the means to calculate energy losses associated with equipment and transmission lines in a transmission system. The loss constants associated with this equipment and transmission lines are available to the compensator, or are preferably pre-stored in the compensator. A meter coupled to the compensator preferably communicates with other meters in the system to net the available supply of energy at the first level of the system. Losses for the second level are then subtracted from this net, which results in a calculation of the net energy available at the second level or second point in the system, downstream of the equipment and/or lines that caused the losses. Losses for a third level are then subtracted from this second net, to arrive at the net energy available at a the third level, and so on.
The present invention thus provides a compensator for computing compensation level losses in an electrical energy transmission system that includes devices to which electrical energy losses can be attributed, i.e., xe2x80x9closs devicesxe2x80x9d such as transformers or transmission lines. The compensator is coupled to a meter located at a first point in the system and in communication with at least one other meter, each such meter at a respective point at the system distal from the first point. The compensator comprises at least one totalizer programmed to receive at least one input relating to a measure of electricity information, to compute a total value of that electricity information, and to output that value. The compensator further comprises a memory device containing at least one loss constant corresponding to a loss device. In, addition, the compensator comprises a loss calculator coupled to the at least one totalizer for receiving an output from the totalizer, and coupled to the memory device for receiving the at least one loss constant from the memory device, and programmed for computing an electrical energy loss value based on the outputs received from the totalizer of totalizers and from the memory device.
The present invention further provides for a compensation method for use in an electrical energy meter coupled to an electrical energy network including loss devices. The energy meter makes at least one measurement relating to electrical energy, and the method compensates the at least one measurement for electrical energy loss due to at least one of the loss devices. This method according to the present invention comprises the steps of selecting a compensation level of the network, determining whether a compensation corresponding to the selected level is to be made to the at least one measurement relating to electrical energy, totalizing the electrical energy measure for at least one of the loss devices, and calculating, based on the result of the totalization step, a loss for the selected level and attributable to the at least one loss device.
A meter coupled to the compensator the present invention thus eliminates the need for additional meters in certain areas of the system, thereby decreasing costs and increasing reliability. A meter coupled to the compensator of the present invention provides detailed information to selected users, customers, managers, and the like, about available energy and losses for multiple levels of the system. In other words, the meters having such a compensator are preferably accessible by suppliers, users, utilities, managers and the like, thereby making usage, losses and metering information available for accounting, study, management, etc.
Consequently, multi-level meters coupled to compensators of the present invention allow power generation facilities and/or utilities to easily and reliably manage and meter the quantity and quality of the energy being delivered and transferred at different locations or levels in a transmission system.